Method and apparatus for testing eyes



April 9, 1940. R. A. SHERMAN 2,196,906

METHOD AND APPARATUS FOR TESTING EYES Filed Nov. 19, 1937 BY AT ORNEYS.

H6. //5 lZ fpNzoR.

Patented Apr. 9, 1940 Reuel A, Sherman, ,Meadville, Pa., assignor toKeystone View-Company, Meadville, Pa., a corporation of Pennsylvania iApplication November 19, 1937', Serial 175,475

8 Claims. (01. 88-20) This invention is directed toa method and ap- Yparatus for gauging a patients ability as to fusion of thesightresponses of botheyes. It affords a simple means where this abilitymay be measured'and readily noted according to a predetermined scale sothat the comparative ability of the patient may be ascertained. f i

In carryingout theinvention a stereoscope is used, andtargetsarepositioned on the two fields presented to the eyes in position to befused if the eyes have the ability to accomplish fusion. Slides in whichthe'target s vary in area are provided and these slidesare presented oneafter the other The invention also contemplates separating the targetsto determine the ability of the patient to- 2!! follow with suchseparation with fusion} For this reason the targets aremade separableand this separation may be checked to a point where fusion is lost andthe ability of the patient given a comparative standing in this respect.Features 80 and details of the invention will appear from thespecification and claims.

A preferred embodiment of the invention and by which the method vmay bepracticed is illustrated in the accompanying drawing as follows: 35 Fig.1 shows a plan view of a stereoscope provided with slides.

Fig. 2 is a side elevation of the same. Fig. 3 a view of the slides asthey appear through the stereoscope. 40 Fig. 4 shows a viewof a slide.

Fig. 5 the fused view as it appears. Fig. 6 'a view in which the slideshave separated to a point where complete fusion is lost.

Fig. '7, slides having similar targets to that of 45 Fig. 4 but of asmaller area.

Fig. 8, slides having targets similar to Figs. 4

and 7 but with targets of a smaller area than, that from the upright lforming a guide-space .9 for receiving the slide. The upper end of theplate 8 is turned over at H] forming a slide groove at the upper edge ofthe plate so that as a slide ll is introduced from the sides of theholderit is 5 carried in'the space 9 and definitely located and vsupported by the inturned portion 10. The sight pathsv leading tothe'fields are'definitely separated by plate 69 carried by the plate 6.v

These slides H,which may be split sdides are 1i).

providedwith targets [2 and i3 oppositely positioned so as to be fusedunder normal conditions and with the targets l4 and 15, one in eachfield, 2 until a'size is reached at which the patients eyes fail toregister fusion. .This critcal point is noted which. have no companiontargets for fusion. In the example shown, the target i2 is a blue-green,16 the target I3 is yellow, and these fuse to a gray or nearly white.The target L4 may bea red and the target l5 a blue.

The reason for fusing the targets ,l2 and I4, of fusing colors ratherthan/depending on m merelyan outlined area, is that in the patients Ireport as to colontheactual existence of fusion can be more definitelychecked. The purposeof v placing on the samefield with each color atar-- I get of different color as l l or I5 is to checkwith certaintywhether-both eyes are seeing the target. so as to be assured that a lackof fusion does not arisefrom. a failure to see one of the targets.

Ithas been found-that fusion is more readily accomplished with largerareas than smaller areas so that starting with a larger area of fusiontargets as in Fig. 4, the patient may be stepped down by a series ofgraduated slides having graduated dimensions, each slide provided withdimensions of predetermined less area until a slide as is reached wherethere is a failure of response in fusion. This may be termed thecritical size or. area of fusion with this particular patient and adefinite empirical standard is adopted so that these measurements may bereadily recorded and the'ability of the patient readily compared withnormal conditions.

To this method and in this apparatus there may be the added testinvolved in the separation of the fused targets so as to determine theability to follow the separation maintaining fusion.

This is accomplished by gradually changing separation of the split sidesand noting the point where fusion ceases, the slides having a scale I8acting in relation to pointers IS on the holder.

Thus in Fig. 5 the fused target l6 will continue to appear until theseparation is beyond the capacity of the patient to follow it, andthelack of fusion will appear as in Fig. 6, the targets there just failingto over-lap and providing a fused p portion [6a, the rest of the targetscarrying their natural colors or shapes.

What I claim as new is:

1. The method of testing fusion ability of the eyes which consists inpresenting to the eyes through a stereoscope, slides having on separatefields fusion target areas, and substituting slides having comparativefusion areas, the fusion areas of the different slides being graduatedin definitely stepped relation as to dimensions, the

relation being such as to some dimensions fusion is achieved and as tosome other dimensions fusion is not achieved and noting the dimensionwhere fusion ceases.

2. The method of testing fusion ability of the eyes which consists inpresenting to the eyes through a stereoscope, slides having on separatefields differently colored fusion target areas, and substituting slideshaving comparative fusion areas, the fusion areas of the differentslides being graduated in definitely stepped relation as to dimensions,the relation being such as to some dimensions fusion is achieved and asto some other dimensions fusion is not achieved and not ing thedimension where fusion ceases.

3. The method of testing fusion ability of the eyes which consists inpresenting to the eyes through a stereoscope, slides having on separatefields fusion target areas, and substituting slides having comparativefusion areas, the fusion areas of the different slidesbeing graduated indefinitely stepped relation as to dimensions, the relation being such asto some dimensions fusion is achieved and as to some other dimensionsfusion is not achieved and noting the dimension where fusion ceases, andvarying the distance betweenthe fusion areas to determine the abilitywhile maintaining fusion. I

4. The method of testing fusion abiilty of the eyes which consists inpresenting to the eyes through a stereoscope slides having on separatefields fusion target areas, and substituting slides having comparativefusion areas, the fusion areas of the different slides being graduatedin definitely stepped relation as-to dimensions, the relation being suchas to some dimensions fusion is achieved and as to some other dimensionsfusion is not achieved and noting'the dimension oscope having meansseparating the sight paths to the fields of view, and a plurality ofslides presenting pairs of comparative fusion targets differentlycolored, the pairs being graduated in area in a definite steppedrelation some slides having targets of areas and spacing adapting themto fuse when viewed and other slides having targets of areas which withthe same spacing adapt them to avoid fusion.

'7. In an apparatus the combination of a stereoscope having meansseparating the sight paths to the fields of view, and a plurality ofslides presenting pairs of comparative fusion targets, the pairs beinggraduated in area in a' definite stepped relation, some slides havingtargets of areas and spacing adapting them to fuse when viewed and otherslides having targets of areas which with the same spacing adapt them toavoid fusion, said slides containing on each field non-fusing targetsaccompanying the fusing targets. v

8. In an apparatus the combination of a stereoscope having meansseparating the sight paths to the fields of view, and a plurality ofslides iJresenting pairs of comparative fusion targets, the pairs beinggraduated in area in a definite stepped relation some slides havingtargets of areas and spacing adapting them to fuse when viewed and otherslides having targets of areas which with the same spacing adapt them toavoid fusion, the units of the pairs of fusion targets being separableto test the extent of sep-' aration with fusion response on the part ofthe;

patient.

- REUEL A. SHERMAN.

